Radio receiving apparatus



Aug. 30, 1932.

E. POWELL 1,875,140

RADIO RECEIVING APPARATUS Filed June 11. 1928 3 Sheets-Sheet 1 INVENTUR.

Edwin L .Powelfl,

Aug. 30, 1932. E. L. POWELL RADIO RECEIVING APPARATUS 5 SheetS Sheet 3 Filed June 11, 1928 J/VIEWTOR.

E'dzvrahL.2?awll vwm. AZTORZVEK Patented Aug. 30, 1932 STATES PATENT OFFEQE EDWIN L. POWELL, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOB, BY MESNE ASSIGNMENTS, T0 WIRED RADIO, INCL, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE Application filed June 11, 1928.

My invention relates. broadly to radio receiving circuits and more specifically to a stabilized arrangement of electron tubes employed for receiving radio signals.

An object of my invention is to provide a, coupling-system for a plurality of electron tubes wherein provision is made for the electrostatic transfer of signalling energy from one radio. frequency circuit to a suc ceeding radio frequency circuit for securing a high degree of selectivity in the operation of the circuits.

Another object of'my invention is to provide a structural arrangement for a radio receiving apparatus wherein means are connected in each of the power supply leads and leads to the sound reproducer for excludingeXtraneo-us currents and protecting the receiving circuits from interference.

Still another object of my invention is to provide a system of electron tubes for radio receiving circuits wherein a coupling device isprovided having a predetermined value of inductance and an adjustable capacity therein for selectively fixing the coupling between the respective circuits of the receiving system.

A further object of my invention is to providea construction of coupling device including an inductance and an adjustable condenser, the condenser being disposed centrally in the coupling device and adjustable by means of a rotatable member extending through the coupling device and operative from the exterior thereof.

An eficient high frequency receiver should be sensitive and selective and capable of being operated in multiple with other receivers on a single antenna without interference from stations other than the one desired to be received. It should continuously cover a wide band of frequencies and give a clear response to either modulated or continuous wave signals without radiation of the local energy employed as the beating and by reference to the accompanying drawings, in which:

RADIO RECEIVING- APPARATUS Serial No. 284,605.

Figure 1 is a diagrammatic illustration of a circuit embodying the. elements of my invention. Fig. 2 is a diagrammatic view showing the electrical balance obtained in the circuits of my invention; Fig. 3 is a side elevation of the coupling device of my invention; Fig. 4 is a cross-sectional view taken through the coupling device illustrated in Fig. 3; Fig. 5 is a cross-sectional view of the capacity adjusting device in the coupling unit of my invention showing the adjusting deviceremoved from the supporting structure of the coupling unit; Fig. 6 is a plan View of the coupling unit with the cover removed; Fig. 7 is a diagrammatic view of the relationship of the several electron tube circuits and the interference prevention circuits employed in the apparatus of my invention; Fig. 8 is a front view of the as- I sembled receiving apparatus; Fig. 9 is a plan view of a portable carrier for coupling units employed in the receiving apparatus, the carrier being partially broken away to illustrate the interior thereof; Fig. 10 is an enlarged plan view of the shielded compartments assembled in the receiving apparatus of my invention. for housing the filter systems; Fig. 11 is a cross-sectional view through one of the filter compartments in the receiving apparatus; and Fig. 12 is a diagrammatic view showing the relationship of filter elements within one of the compartments.

My invention comprises an autodyne de tector circuit 4: capacitively coupled to a tuned stage of radio frequency amplification 3 and supplemented by two stages of audio frequency amplification 7, 8. Plug in coils 12 and 18 for the radio frequency amplifier 3 and 55 and 13 for the detector or rectifier 4, respectively, give the equipment a wide tuning range. The degree of regeneration or strength of oscillation in the detector circuit 1 is controlled by a variable resistor 17 which connects in series with the tickle-r winding 13 included in the structure of each receiver coil.

Among the advantages of my system as compared with others. are that with the system I employ radiation is effectually pre- .IIIOI l as,

5 pling; Z), separate shielding of theantenna input 23 and of the radio frequency amplifier circuits 3; 0, elimination .of the detector circuit oscillations from all battery circuits 24: and telephone31 is accomplished through the medium of a filt-er system havi'ngrenewable cartridgetype chokes 25 built intobut individually shielded from the receiver compartment; d, elimination of the detector cir-- 'cuit oscillations from all battery leads to fectedthrough .theimedium of an additional similar. filter system 26 builtfintojb ut individually 'shieded from theradio frequency amplifier compartmentianii I employ a I method for complete neutralization of capac itive coupling .to the antenna 23 through the radio frequency amplifier tube 3. A system of the type shown in Fig. 2, is used for; this 7 purpose, it being a true. bridge in which all I four arms are'ca'pacitive. This is asy'stemi which compensates for both the grid-filamerit and grid-plate capacitiesin the tube,

f two adjustable condensers 20 and'19 being employed between the low potential .oendof' the tuned grid. input circuit 12, 21 and" the j filament and plate terminals respectively'of the. radio frequencyainplifying tube 3.

Figs. 3,4, -5 and6 show a method of coil structure the coil form 27, 27a 'includingia 'ance 12, balancing condenser comprising f members 28. 40, and 38, and coil connecting balancing con- I plugs 22; Fig. 5, shows the denser adjusting screw 28, having an inter-. nally threaded bore 37 and having a flange 36 at'thelower end'thereof. Threaded stud 39 which may be integral withfcontact plug 22,: is electrically connected to' a'condenser plate 40. .A second condenser plate 38, which has a suitable inherent .resiliency'or spring tension is secured to the base il by means of a second contact "plug. 22a. Condenser plates4c0 and 38"are insulated electrically from each; other by any. suitable dielectric V 30, wh ch can be ofjmic'a. Threaded bore "37 is rotatable over the threaded 'studj 39.

' I F lange. 36 "of-threaded member .37 engages I the'upturned edge ofcondenser plate 38. 7 By adjusting the coupling bore 37 and threadedstud 39,,condens'er Plates- 38 and 40 are brought in closer Yrela tion and the capacity of the, condenser, is

thereby increased. I V. V r o Fig. 6 is an illustration showing a plan view I I ofthe coi'l structure, one of the condenser plates 38, adjusting screw 28, fiangei36, con' tact'plugs 22 and 22a, coil form27a and-coaer1 Fig. anillustration showingfthe coil un t mounted onan insulated sub-panel .46

: F 5 andl contact plugs;22"'and 22a, forming con;

the radio frequency amplifier circuit3 is ef'- ,3 and 4c. Theseconnecting' plugs and jacks couplingcoil winding 18, gridcircuit induct between threaded and illustrates how contact plugs 22 are'con- I nected to thevcoil windings and vacuum tube e circuits. Fig. 2 is a schematic diagram of a bridge circuit. showing inter-electrode ca- 7 pacities C Caofthethermion'ic vacuum tubes II 3 or 4, the capacity Q corresponding to refer--- ence character 20 of Fig. 7,-G corresponding T 7 to reference character 19 of Fig. 7. =As shown in Fig. 7 capacity'20 is includedin the interchangeable coil unit and corresponds 'to'the adjustable capacity unitillustrated' on an enlarged scale inFig. 5. r V a 1 Connecting plu'gs and jacks 35 illustrated in Fig.7 provide interconnection between the power and filter circuits 24', 25, 26, 32 and the individually shieldedcir'cuits ofthe the mionic vacuum tubes 3, 4t, Zand 8 respectively. The. same type of connecting plugs'and acks 35 are employed for-connecting the antennaground system 51 to-"the receiving system I proper, and for inter-coupling the radio, frequency circuits gof thermionicvacuumtubes 35are also shown in Figs; 10, 1'1 and 12. v y

Reference character .14 ofjFig. 7-identifies a plate or'free-end coil electrostatically cou-r pled to 'ind'uctance55. Thisjplate 'correspondsto'plat'e 38 of 5" and'may; beconstructedthe same as the. condenser in Fig.1'5

' by employing a second plate sOconnectedto I the inductanceco'il 55. "This capacity ;pro-

vides the proper coupling to the gridc'ircuit f ofthe'detector tube and is matched with the I inductance unitupon -..which' it is "mounted. s Fig. 7 also shows the individual shielding 1 of the radio frequencyarnplifier 3, of the de; tector a, theaudiofrequency amplifier '7' and -8,and theindividual filter systems-25, 26 and @1057 32. 8 shows a front view of'asuitable:

cabinet for the equipment with the" various '5 3 controls mounted therejon. .Handles 33 are provided on the panel f OrQI'emm' ing"the, ap

paratns from the cabinetiand replacingithj d 7 therein. Fig. -9"sho'ws an illustration of'i'a; I suitablecarryingjcase for the coilsemployed" V in my system; Fig. 10 showsan' illustration i of the filtering systems 25 'and 26'showingindividually shielded compartments lfor. neu: 1

tralizing the stray of"thelfilter coils. 7

'llshows a fragmentary View partially, V

in cross section of'the shielded compartment-V Q 1 enclosing the filter systems 25 and 2 6 Figjl2shows another illustration eras filter m systems 25 and 26 and individually shielded compartments 1 for neutralizing any stray I field of the filter coils or induction-from the radio frequency, detector and audio fre emy compartments lndividualshielding I is essential to efiicient operation thus reduc ing a'll inter-stage couplin'p and assisting neuf;

tcapacitlesof tralization of theinter-elemen the acuum, tubesemployed;

i In. all neutralizing systems, howeyer, the li q 1 condition for balance is not dependent solely onthe inter-element capacities of the vacuum tube employed, the circuits associated therewith having a considerable efiect on the balance adjustment. Thus, a receiving system employing a stepped inductance, or plug-in coils, must be rebalanced for every change in circuit inductance as well as for tube replacements. A possible remedy for this con dition would be to provide a plurality of balancing condensers, one for each value of inductance; but, in the case of such a neutralizing system, all these condensers would have to be readjusted for each tube renewal. The operation of my system has been made practical and the efiiciency improved by incorporating a condenser comprising the filament leg of the balance system in each of the plug-in radio frequency amplifier coils and mounting a single condenser forming the plate leg of the system on the radio frequency amplifier panel. In the initial test of the equipment the filament condensers in each plug-in coil are adjusted against a given setting of the plate condenser and sealed. This is done with the equipment connected to a given antenna installation and with a given radio frequency amplifier tube, and gives a permanent automatic compensation for the reactive effect of changing inductances during operation. Thereafter in'service, it is only necessary to readjust the single condenser in the plate leg of the neutralizing circuit against the setting of the filament condenser on any one coil in order to compensate for the variation in neutralization on all coils which may result from a tube replacement or any change in the characteristics of the antenna circuit.

It is to be understood that I do not limit my invention to the description and circuit arrangement illustrated in the accompany ing drawings. The embodiments of my intube having grid, filament and plate circuits,

tuning means provided in said grid circuit, a variable capacity for neutralizing lnterelectrode capacity of said thermionic vacuum tube, said neutralizing capacity being mount-- ed on said tuning means and means for interchanging said tuning means in said circuit without readjusting said neutralizing means for widely different frequencies of said signaling energy. 7

2. In a system for receiving signaling energy, thermionic vacuum tubes for amplifying and rectifying said signaling energy, said thermionic tubes having grid, filament mg means mounted on each of said interchangeable inductance coils whereby said first neutralizing means, without adjustment, provides uniform neutralization of said circuits for a wide band of frequencies.

3. In a system for receiving signaling energy, thermionic vacuum tube amplifiers and rectifiers and associated grid and plate circuits, interchangeable coils for the grid circuit of one of said amplifier tubes to cause it to operate on a wide band of frequencies, and adjustable neutralizing condensers, one of which is mounted on each of said interchangeable coils for effecting uniform neutralization of the system over a wide band of frequencies.

4. In a system for receiving signaling energy the combination of thermionic vacuum tubes having grid, filament and plate circuits, interchangeable inductance coils for the grid circuit of one of said tubes and neutralizing means for neutralizing the interelectrode capacity of said tube said neutralizing means being mounted on one of said inductance coils for effecting uniform neutralization of said inter-electrode capacity irrespective of any selected interchangeable coil.

5. In a system for receiving signaling energy, a thermionic vacuum tube and associated grid and plate circuits, a circuit for supplying said signaling energy to said grid circuit, interchangeable coils for said grid circuit, separate means included in each of said interchangeable coils for neutralizing the inter-electrode capacities of said thermionic tube.

6. In a system for receiving signaling energy, separately shielded thermionic vacuum tube amplifiers and rectifiers, interchangeable coils for the grid circuits of said thermionic tubes, a neutralizing condenser mounted within each of the interchangeable coils for one at least of said tubes for neutralizing the inter-electrode capacity of that tube, and a coupling coil included in each of said interchangeable coils for effecting proper neutralization and coupling between the source of said signaling energy and said vacuum tube circuits over a wide band of frequencies.

7. In a system for receiving signaling energy comprising individually shielded amplifying, rectifying and power supply circuits, interchangeable coil units for said amplifying and rectifying means, contact plugs on said coils for making contact with said amplifying and rectifying means, a rotatable member having a threaded bore disposed centrally in each removable coil unit, a stationary plate and a movable plate, said movable plate connected to one of said contact plugs, said stationary plate electrically connected to an- '4 Wmw EDWIN L." POWELL. 

